Opinels are just perfectly functional cheap knives. My wife likes them. There are stainless blades now as well as the carbon steel variety. At home we keep an Opinel in a little tray on the kitchen table for opening packaging and things like that, but I'd never take it camping.
When you start talking about other makes you can go from less than a tenner to several hundred for what is essentially the same thing -- a folding knife. It really depends what floats your particular boat. I'm not the world's biggest fan of Opinels, but likewise, although there's nothing really wrong with them, most Buck folders don't really do it for me, and much as I hate to say it neither do some of the Wengers. I like some of the Buck fixed blade hunters, and my Victorinox SwissTool is probably my all time favourite tool although I'm not greatly enamoured of the knife blades on it (they just do the job) and a proper folder will always be more comfortable. Having said that I'm more interested in the materials, the construction and how it feels in the hand than in who made it. I prefer stainless blades, especially if I'm going to use them for food preparation and/or in the wet, which happens more often than I'd like I suppose. I like as small a blade as will do the job, most often full flat with very little convexity on the edge. For me it
must have a lock for safety, and I like a back lock. As for the brand, usually it's whatever will get me a lasting product at a reasonable price. I have a couple of EKA folders (12c27 blades) that I wouldn't want to part with, and one of them usually goes camping with me. Most of the time I use a multi-tool because there's always one handy on my belt. They're not the cheapest way of getting a serviceable folding knife but they more than make up for it with their versatility.
Choosing most tools, and especially a knife, is a very personal thing. You need a good idea of what it will be asked to do. You really need to handle a few, maybe buy one that you think you'll like and use it for a while to see what you like and what you don't like about it in use. You might be lucky and fall in love -- I was lucky that way with the EKA -- but you might just not get on with it and have to put an ad in the classified section, then get one that you think is closer to your ideal. Think about what you're going to use it for. Think about shape and size, grind, lock type if it's folder, how it feels in the hand, maintenance. Oh, and think about the cost.
